The present invention relates to the use of radiation sensitive sensors to detect physical phenomenon such as emergent forest fires.
The use of a solar power, microprocessor based sensor system is known from U.S. Pat. No. 5,229,649 which discloses a light energized energy management system used to powers an irrigation system. The system employs a photovoltaic module approximately 18 inches square which generates power from incident light stored and stores such power in supercapacitors. A transportable battery power source is connected to the controller to power communication for manual operation and for loading of irrigation control programs. At the end of each communication, upon removal of the transportable battery power source, the internal supercapacitor energy storage source is left fully charged. The controller remains in sleep mode consuming minimal energy. A real time clock, which is updated at brief milliseconds of sporadic time intervals for scheduled irrigation control, is the only energy used. Once a minute, the sytem comes out of sleep mode to check if watering activity is required. The power storage of the capacitors is approximately 6.5 mWH. The sporadically operated irrigation control uses less than 6.4 mWH per day with remaining energy expended by to 128 ultra-low-power valve activations per night from existing stored energy.
The methodology of energy management from full energy to zero energy and back to full energy at energy rates of change microwatts per minute is disclosed in U.S. Pat. No. 5,661,349. This controller provides a seamless accumulation of energy in order to smoothly progress from an inoperative unpowered condition to an operative powered condition. The device progresses to operability in spite of not only being totally devoid of received energy at various times but also being subject to a very slow accrual of energy over a period of days, weeks or months. A power monitor circuit is constructed from electrical circuit technology, which is operative at relatively low voltage levels, such as BICMOS technology. Other electrical devices are operative only at relatively high voltage levels and are typically made from CMOS technology. When power is marginal, the low-operational-voltage energy monitoring circuit reliably produces one or more status signals well before the other, higher-operational voltage circuits begin to operate. Therefore the electronic device of the '349 patent degrades and de-energizes smoothly. With respect to this particular application, the microprocessor based irrigation controller closes all controlled irrigation valves before reverting to housekeeping and minimal energy consumption during declining energy. Then, with further diminishing power, becomes dormant. Controller re-assumes full operability when energy balances permit.
It is an object of the present invention to provide a self-contained outdoor terrestrial vandal proof forest fire sensor for remote sensing and accurate reporting of incipient forest fires and to provide radio reporting alarms having reliable recognition of forest fire ignition events.
It is another object of the present invention to provide a grid array of control centers, which individually and collectively report to regional and/or national base stations. Communication occurs through radio repeater or satellite links and/or normal communication links such as telephone wires and/or internet links which are able to function with thousands of sensors. The sensor array allow for accurate reporting which covers hundreds of square miles of area in a timely manner to preclude spreading of the fire even under adverse dry and windy “fire season” conditions, thereby allowing employment of aircraft dropping retardant or fire jumpers. The sensors operate around the clock and each sensor allows for early detection while retaining accuracy to avoid an unacceptable rate of false alarms.
It is the further object of the present invention to provide that each fire sensor functions individually without involvement of remote computers or humans to detect the very earliest stages of forest fires and to be able to discriminate forest fires from other occurrences.
The detector system of the present invention uses a single solid state radiation sensor to detect radiation emission of a particular frequency known as the CO2 spike which accompanies combustion of carbonaceous materials and particularly vegetation and trees in forest fires. According to the present invention, a single fixed radiation sensor receives radiation from a mirror that rotates through a series of angular positions in the horizontal plane of the earth.
The mirror covers an elevational angle of between +45 degrees and −45 degrees from the horizontal position in order to “look” at a vertical “slice” of terrain and sky.
According to a preferred embodiment, the incremental rotation of the mirror receiving infrared radiation through a sapphire window allows for the use of a single detector to sweep an entire 360° looking for a particular CO2 spike exhibiting specific frequency variations in order to detect fire combustion.
It is a further object of the invention to provide signal processing of the output of the detector in order to control movement of the mirror as a function of the strength, duration and frequency of the signal.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.